Synthesis and crystal structure of tetranuclear copper(I) and silver(I) complexes bridged by 2-amino-1,3,4-thiadiazole (atdz):: [Cu4(atdz)6](ClO4)4 • 2CH3OH and [Ag4(atdz)6](ClO4)4

Two novel tetracopper(I) and tetrasilver(I) complexes [Cu-4(atdz)(6)](ClO4)(4). 2CH(3)OH (1) and [Ag-4(atdz)(6)](ClO4)(4) (2), have been prepared using 2-amino-1,3,4-thiadiazole (atdz), and their crystal structures and properties have been determined. On each tetranuclear complex, two Cu or Ag atoms (M) are bridged by two atdz ligands to form a six-membered N2M2N2 framework. The two N2M2N2 frameworks are in parallel linked by another atdz ligand to provide the tetranuclear structure with a rectangular M-4 core. The four Cu or Ag atoms possess a trigonal-square geometry. The two adjacent M...M separations are (3.096(1) and 3.412(1) Angstrom) and (3.316(2) and 3.658(2) Angstrom) for 1 and 2, respectively. On both tetranuclear complexes there are two species of hydrogen bonds between the ClO4- anions and the NH2 group of atdz ligands. It is proposed that the hydrogen bonds are related to the stabilization of the tetranuclear structure during the crystallization process. (C) 1999 Elsevier Science S.A. All rights reserved.